Comparison of Historical Water Temperature Measurements with Landsat Analysis Ready Data Provisional Surface Temperature Estimates for the Yukon River in Alaska

Water temperature is a key element of freshwater ecological systems and a critical element within natural resource monitoring programs. In the absence of in situ measurements, remote sensing platforms can indirectly measure water temperature over time and space. The Earth Resources Observation and Science (EROS) Center has processed archived Landsat imagery into analysis ready data (ARD), including Level-2 Provisional Surface Temperature (pST) estimates derived from the Landsat 4–5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and Landsat 8 Thermal Infrared Sensor (TIRS). We compared in situ measurements of water temperature within the Yukon River in Alaska with 52 instances of pST estimates between June 2014 and September 2020. Agreement was good with an RMSE of 2.25 °C and only a slight negative bias in the estimated mean daily water temperature of −0.47 °C. For the 52 dates compared, the average daily water temperature measured by the USGS streamgage was 11.3 °C with a standard deviation of 5.7 °C. The average daily pST estimate was 10.8 °C with a standard deviation of 6.1 °C. At least in the case of large unstratified rivers in Alaska, ARD pST can be used to infer water temperature in the absence of or in tandem with ground-based water temperature monitoring campaigns.

Characteristics of daily water temperature fluctuations in lake kierskie (West Poland)

The paper presents the dynamics of daily water temperature fluctuations in Lake Kierskie (West Poland) and determines the effect of air temperatures and wind speed on the variability of the parameter (water temperature). The analysis was based on hourly water temperature values from the period from May 2012 to January 2018. The data analysis permitted the description of the thermal regime of waters in the lake in the hourly cycle in reference to each month, and designation of months characterised by the highest and lowest stability of water temperatures. More than half of the analysed days was characterised by a change in water temperature not exceeding 1°C. The course of water temperature showed strongly positive correlations with air temperature, and weak correlations with wind speed. Water temperatures in the lake were correlated the strongest with air temperatures with a 24 h time step.